If you drive around in a car with "Cops are Pigs" painted on it, do you think you'll draw some extra attention from police?

Yes, I think I would draw extra attention from police if I were to do that. And if there was any indication that their attention violated my rights or that it was improperly focused, I'd want the police warned, corrected, retrained and/or disciplined, depending on the severity of their transgression(s). That's so obvious a response that I'm virtually certain that everyone here would agree.